Revert "Squashed - Removal of PID functional range"

Marlin/Configuration.h

 // Comment the following line to disable PID and enable bang-bang.
 #define PIDTEMP
 #define BANG_MAX 255 // limits current to nozzle while in bang-bang mode; 255=full current
-#define PID_MAX BANG_MAX // limits current to nozzle while PID is active); 255=full current
+#define PID_MAX BANG_MAX // limits current to nozzle while PID is active (see PID_FUNCTIONAL_RANGE below); 255=full current
 #if ENABLED(PIDTEMP)
   //#define PID_AUTOTUNE_MENU // Add PID Autotune to the LCD "Temperature" menu to run M303 and apply the result.
   //#define PID_DEBUG // Sends debug data to the serial port.
   //#define SLOW_PWM_HEATERS // PWM with very low frequency (roughly 0.125Hz=8s) and minimum state time of approximately 1s useful for heaters driven by a relay
   //#define PID_PARAMS_PER_HOTEND // Uses separate PID parameters for each extruder (useful for mismatched extruders)
                                   // Set/get with gcode: M301 E[extruder number, 0-2]
+  #define PID_FUNCTIONAL_RANGE 10 // If the temperature difference between the target temperature and the actual temperature
+                                  // is more than PID_FUNCTIONAL_RANGE then the PID will be shut off and the heater will be set to min/max.
   #define K1 0.95 //smoothing factor within the PID
 
   // If you are using a pre-configured hotend then you can use one of the value sets by uncommenting it

Marlin/example_configurations/Cartesio/Configuration.h

 // Comment the following line to disable PID and enable bang-bang.
 #define PIDTEMP
 #define BANG_MAX 255 // limits current to nozzle while in bang-bang mode; 255=full current
-#define PID_MAX BANG_MAX // limits current to nozzle while PID is active; 255=full current
+#define PID_MAX BANG_MAX // limits current to nozzle while PID is active (see PID_FUNCTIONAL_RANGE below); 255=full current
 #if ENABLED(PIDTEMP)
   //#define PID_AUTOTUNE_MENU // Add PID Autotune to the LCD "Temperature" menu to run M303 and apply the result.
   //#define PID_DEBUG // Sends debug data to the serial port.
   //#define SLOW_PWM_HEATERS // PWM with very low frequency (roughly 0.125Hz=8s) and minimum state time of approximately 1s useful for heaters driven by a relay
   //#define PID_PARAMS_PER_HOTEND // Uses separate PID parameters for each extruder (useful for mismatched extruders)
                                   // Set/get with gcode: M301 E[extruder number, 0-2]
+  #define PID_FUNCTIONAL_RANGE 10 // If the temperature difference between the target temperature and the actual temperature
+                                  // is more than PID_FUNCTIONAL_RANGE then the PID will be shut off and the heater will be set to min/max.
   #define K1 0.95 //smoothing factor within the PID
 
   // If you are using a pre-configured hotend then you can use one of the value sets by uncommenting it

Marlin/example_configurations/Felix/Configuration.h

 // Comment the following line to disable PID and enable bang-bang.
 #define PIDTEMP
 #define BANG_MAX 255 // limits current to nozzle while in bang-bang mode; 255=full current
-#define PID_MAX BANG_MAX // limits current to nozzle while PID is active; 255=full current
+#define PID_MAX BANG_MAX // limits current to nozzle while PID is active (see PID_FUNCTIONAL_RANGE below); 255=full current
 #if ENABLED(PIDTEMP)
   //#define PID_AUTOTUNE_MENU // Add PID Autotune to the LCD "Temperature" menu to run M303 and apply the result.
   //#define PID_DEBUG // Sends debug data to the serial port.
   //#define SLOW_PWM_HEATERS // PWM with very low frequency (roughly 0.125Hz=8s) and minimum state time of approximately 1s useful for heaters driven by a relay
   //#define PID_PARAMS_PER_HOTEND // Uses separate PID parameters for each extruder (useful for mismatched extruders)
                                   // Set/get with gcode: M301 E[extruder number, 0-2]
+  #define PID_FUNCTIONAL_RANGE 10 // If the temperature difference between the target temperature and the actual temperature
+                                  // is more than PID_FUNCTIONAL_RANGE then the PID will be shut off and the heater will be set to min/max.
   #define K1 0.95 //smoothing factor within the PID
 
   // Felix 2.0+ electronics with v4 Hotend

Marlin/example_configurations/Felix/DUAL/Configuration.h

 // Comment the following line to disable PID and enable bang-bang.
 #define PIDTEMP
 #define BANG_MAX 255 // limits current to nozzle while in bang-bang mode; 255=full current
-#define PID_MAX BANG_MAX // limits current to nozzle while PID is active; 255=full current
+#define PID_MAX BANG_MAX // limits current to nozzle while PID is active (see PID_FUNCTIONAL_RANGE below); 255=full current
 #if ENABLED(PIDTEMP)
   //#define PID_AUTOTUNE_MENU // Add PID Autotune to the LCD "Temperature" menu to run M303 and apply the result.
   //#define PID_DEBUG // Sends debug data to the serial port.
   //#define SLOW_PWM_HEATERS // PWM with very low frequency (roughly 0.125Hz=8s) and minimum state time of approximately 1s useful for heaters driven by a relay
   //#define PID_PARAMS_PER_HOTEND // Uses separate PID parameters for each extruder (useful for mismatched extruders)
                                   // Set/get with gcode: M301 E[extruder number, 0-2]
+  #define PID_FUNCTIONAL_RANGE 10 // If the temperature difference between the target temperature and the actual temperature
+                                  // is more than PID_FUNCTIONAL_RANGE then the PID will be shut off and the heater will be set to min/max.
   #define K1 0.95 //smoothing factor within the PID
 
   // Felix 2.0+ electronics with v4 Hotend

Marlin/example_configurations/Hephestos/Configuration.h

 // Comment the following line to disable PID and enable bang-bang.
 #define PIDTEMP
 #define BANG_MAX 255 // limits current to nozzle while in bang-bang mode; 255=full current
-#define PID_MAX BANG_MAX // limits current to nozzle while PID is active; 255=full current
+#define PID_MAX BANG_MAX // limits current to nozzle while PID is active (see PID_FUNCTIONAL_RANGE below); 255=full current
 #if ENABLED(PIDTEMP)
   //#define PID_AUTOTUNE_MENU // Add PID Autotune to the LCD "Temperature" menu to run M303 and apply the result.
   //#define PID_DEBUG // Sends debug data to the serial port.
   //#define SLOW_PWM_HEATERS // PWM with very low frequency (roughly 0.125Hz=8s) and minimum state time of approximately 1s useful for heaters driven by a relay
   //#define PID_PARAMS_PER_HOTEND // Uses separate PID parameters for each extruder (useful for mismatched extruders)
                                   // Set/get with gcode: M301 E[extruder number, 0-2]
+  #define PID_FUNCTIONAL_RANGE 10 // If the temperature difference between the target temperature and the actual temperature
+                                  // is more than PID_FUNCTIONAL_RANGE then the PID will be shut off and the heater will be set to min/max.
   #define K1 0.95 //smoothing factor within the PID
 
   // Hephestos i3

Marlin/example_configurations/Hephestos_2/Configuration.h

 // Comment the following line to disable PID and enable bang-bang.
 #define PIDTEMP
 #define BANG_MAX 255 // limits current to nozzle while in bang-bang mode; 255=full current
-#define PID_MAX BANG_MAX // limits current to nozzle while PID is active; 255=full current
+#define PID_MAX BANG_MAX // limits current to nozzle while PID is active (see PID_FUNCTIONAL_RANGE below); 255=full current
 #if ENABLED(PIDTEMP)
   //#define PID_AUTOTUNE_MENU // Add PID Autotune to the LCD "Temperature" menu to run M303 and apply the result.
   //#define PID_DEBUG // Sends debug data to the serial port.
   //#define SLOW_PWM_HEATERS // PWM with very low frequency (roughly 0.125Hz=8s) and minimum state time of approximately 1s useful for heaters driven by a relay
   //#define PID_PARAMS_PER_HOTEND // Uses separate PID parameters for each extruder (useful for mismatched extruders)
                                   // Set/get with gcode: M301 E[extruder number, 0-2]
+  #define PID_FUNCTIONAL_RANGE 250  // If the temperature difference between the target temperature and the actual temperature
+                                    // is more than PID_FUNCTIONAL_RANGE then the PID will be shut off and the heater will be set to min/max.
   #define K1 0.95 //smoothing factor within the PID
 
   // Tuned PID values using M303

Marlin/example_configurations/K8200/Configuration.h

 // Comment the following line to disable PID and enable bang-bang.
 #define PIDTEMP
 #define BANG_MAX 255 // limits current to nozzle while in bang-bang mode; 255=full current
-#define PID_MAX BANG_MAX // limits current to nozzle while PID is active; 255=full current
+#define PID_MAX BANG_MAX // limits current to nozzle while PID is active (see PID_FUNCTIONAL_RANGE below); 255=full current
 #if ENABLED(PIDTEMP)
   //#define PID_AUTOTUNE_MENU // Add PID Autotune to the LCD "Temperature" menu to run M303 and apply the result.
   //#define PID_DEBUG // Sends debug data to the serial port.
   //#define SLOW_PWM_HEATERS // PWM with very low frequency (roughly 0.125Hz=8s) and minimum state time of approximately 1s useful for heaters driven by a relay
   //#define PID_PARAMS_PER_HOTEND // Uses separate PID parameters for each extruder (useful for mismatched extruders)
                                   // Set/get with gcode: M301 E[extruder number, 0-2]
+  #define PID_FUNCTIONAL_RANGE 10 // If the temperature difference between the target temperature and the actual temperature
+                                  // is more than PID_FUNCTIONAL_RANGE then the PID will be shut off and the heater will be set to min/max.
   #define K1 0.95 //smoothing factor within the PID
 
   // If you are using a pre-configured hotend then you can use one of the value sets by uncommenting it

Marlin/example_configurations/K8400/Configuration.h

 // Comment the following line to disable PID and enable bang-bang.
 #define PIDTEMP
 #define BANG_MAX 255 // limits current to nozzle while in bang-bang mode; 255=full current
-#define PID_MAX BANG_MAX // limits current to nozzle while PID is active; 255=full current
+#define PID_MAX BANG_MAX // limits current to nozzle while PID is active (see PID_FUNCTIONAL_RANGE below); 255=full current
 #if ENABLED(PIDTEMP)
   //#define PID_AUTOTUNE_MENU // Add PID Autotune to the LCD "Temperature" menu to run M303 and apply the result.
   //#define PID_DEBUG // Sends debug data to the serial port.
   //#define SLOW_PWM_HEATERS // PWM with very low frequency (roughly 0.125Hz=8s) and minimum state time of approximately 1s useful for heaters driven by a relay
   //#define PID_PARAMS_PER_HOTEND // Uses separate PID parameters for each extruder (useful for mismatched extruders)
                                   // Set/get with gcode: M301 E[extruder number, 0-2]
+  #define PID_FUNCTIONAL_RANGE 10 // If the temperature difference between the target temperature and the actual temperature
+                                  // is more than PID_FUNCTIONAL_RANGE then the PID will be shut off and the heater will be set to min/max.
   #define K1 0.95 //smoothing factor within the PID
 
   // If you are using a pre-configured hotend then you can use one of the value sets by uncommenting it

Marlin/example_configurations/K8400/Dual-head/Configuration.h

 // Comment the following line to disable PID and enable bang-bang.
 #define PIDTEMP
 #define BANG_MAX 255 // limits current to nozzle while in bang-bang mode; 255=full current
-#define PID_MAX BANG_MAX // limits current to nozzle while PID is active; 255=full current
+#define PID_MAX BANG_MAX // limits current to nozzle while PID is active (see PID_FUNCTIONAL_RANGE below); 255=full current
 #if ENABLED(PIDTEMP)
   //#define PID_AUTOTUNE_MENU // Add PID Autotune to the LCD "Temperature" menu to run M303 and apply the result.
   //#define PID_DEBUG // Sends debug data to the serial port.
   //#define SLOW_PWM_HEATERS // PWM with very low frequency (roughly 0.125Hz=8s) and minimum state time of approximately 1s useful for heaters driven by a relay
   //#define PID_PARAMS_PER_HOTEND // Uses separate PID parameters for each extruder (useful for mismatched extruders)
                                   // Set/get with gcode: M301 E[extruder number, 0-2]
+  #define PID_FUNCTIONAL_RANGE 10 // If the temperature difference between the target temperature and the actual temperature
+                                  // is more than PID_FUNCTIONAL_RANGE then the PID will be shut off and the heater will be set to min/max.
   #define K1 0.95 //smoothing factor within the PID
 
   // If you are using a pre-configured hotend then you can use one of the value sets by uncommenting it

Marlin/example_configurations/RepRapWorld/Megatronics/Configuration.h

 // Comment the following line to disable PID and enable bang-bang.
 #define PIDTEMP
 #define BANG_MAX 255 // limits current to nozzle while in bang-bang mode; 255=full current
-#define PID_MAX BANG_MAX // limits current to nozzle while PID is active; 255=full current
+#define PID_MAX BANG_MAX // limits current to nozzle while PID is active (see PID_FUNCTIONAL_RANGE below); 255=full current
 #if ENABLED(PIDTEMP)
   //#define PID_AUTOTUNE_MENU // Add PID Autotune to the LCD "Temperature" menu to run M303 and apply the result.
   //#define PID_DEBUG // Sends debug data to the serial port.
   //#define SLOW_PWM_HEATERS // PWM with very low frequency (roughly 0.125Hz=8s) and minimum state time of approximately 1s useful for heaters driven by a relay
   //#define PID_PARAMS_PER_HOTEND // Uses separate PID parameters for each extruder (useful for mismatched extruders)
                                   // Set/get with gcode: M301 E[extruder number, 0-2]
+  #define PID_FUNCTIONAL_RANGE 10 // If the temperature difference between the target temperature and the actual temperature
+                                  // is more than PID_FUNCTIONAL_RANGE then the PID will be shut off and the heater will be set to min/max.
   #define K1 0.95 //smoothing factor within the PID
 
   // If you are using a pre-configured hotend then you can use one of the value sets by uncommenting it

Marlin/example_configurations/RigidBot/Configuration.h

 // Comment the following line to disable PID and enable bang-bang.
 #define PIDTEMP
 #define BANG_MAX 255 // limits current to nozzle while in bang-bang mode; 255=full current
-#define PID_MAX BANG_MAX // limits current to nozzle while PID is active; 255=full current
+#define PID_MAX BANG_MAX // limits current to nozzle while PID is active (see PID_FUNCTIONAL_RANGE below); 255=full current
 #if ENABLED(PIDTEMP)
   //#define PID_AUTOTUNE_MENU // Add PID Autotune to the LCD "Temperature" menu to run M303 and apply the result.
   //#define PID_DEBUG // Sends debug data to the serial port.
   //#define SLOW_PWM_HEATERS // PWM with very low frequency (roughly 0.125Hz=8s) and minimum state time of approximately 1s useful for heaters driven by a relay
   //#define PID_PARAMS_PER_HOTEND // Uses separate PID parameters for each extruder (useful for mismatched extruders)
                                   // Set/get with gcode: M301 E[extruder number, 0-2]
+  #define PID_FUNCTIONAL_RANGE 10 // If the temperature difference between the target temperature and the actual temperature
+                                  // is more than PID_FUNCTIONAL_RANGE then the PID will be shut off and the heater will be set to min/max.
   #define K1 0.95 //smoothing factor within the PID
 
   // If you are using a pre-configured hotend then you can use one of the value sets by uncommenting it

Marlin/example_configurations/SCARA/Configuration.h

 // Comment the following line to disable PID and enable bang-bang.
 #define PIDTEMP
 #define BANG_MAX 255 // limits current to nozzle while in bang-bang mode; 255=full current
-#define PID_MAX BANG_MAX // limits current to nozzle while PID is active; 255=full current
+#define PID_MAX BANG_MAX // limits current to nozzle while PID is active (see PID_FUNCTIONAL_RANGE below); 255=full current
 #if ENABLED(PIDTEMP)
   //#define PID_AUTOTUNE_MENU // Add PID Autotune to the LCD "Temperature" menu to run M303 and apply the result.
   //#define PID_DEBUG // Sends debug data to the serial port.
   //#define SLOW_PWM_HEATERS // PWM with very low frequency (roughly 0.125Hz=8s) and minimum state time of approximately 1s useful for heaters driven by a relay
   //#define PID_PARAMS_PER_HOTEND // Uses separate PID parameters for each extruder (useful for mismatched extruders)
                                   // Set/get with gcode: M301 E[extruder number, 0-2]
+  #define PID_FUNCTIONAL_RANGE 20 // If the temperature difference between the target temperature and the actual temperature
+                                  // is more than PID_FUNCTIONAL_RANGE then the PID will be shut off and the heater will be set to min/max.
   #define K1 0.95 //smoothing factor within the PID
 
   // Merlin Hotend: From Autotune

Marlin/example_configurations/TAZ4/Configuration.h

 // Comment the following line to disable PID and enable bang-bang.
 #define PIDTEMP
 #define BANG_MAX 70 // limits current to nozzle while in bang-bang mode; 255=full current
-#define PID_MAX 74 // limits current to nozzle while PID is active; 255=full current
+#define PID_MAX 74 // limits current to nozzle while PID is active (see PID_FUNCTIONAL_RANGE below); 255=full current
 #if ENABLED(PIDTEMP)
   //#define PID_AUTOTUNE_MENU // Add PID Autotune to the LCD "Temperature" menu to run M303 and apply the result.
   //#define PID_DEBUG // Sends debug data to the serial port.
   //#define SLOW_PWM_HEATERS // PWM with very low frequency (roughly 0.125Hz=8s) and minimum state time of approximately 1s useful for heaters driven by a relay
   //#define PID_PARAMS_PER_HOTEND // Uses separate PID parameters for each extruder (useful for mismatched extruders)
                                   // Set/get with gcode: M301 E[extruder number, 0-2]
+  #define PID_FUNCTIONAL_RANGE 16 // If the temperature difference between the target temperature and the actual temperature
+                                  // is more than PID_FUNCTIONAL_RANGE then the PID will be shut off and the heater will be set to min/max.
   #define K1 0.95 //smoothing factor within the PID
 
   // If you are using a pre-configured hotend then you can use one of the value sets by uncommenting it

Marlin/example_configurations/WITBOX/Configuration.h

 // Comment the following line to disable PID and enable bang-bang.
 #define PIDTEMP
 #define BANG_MAX 255 // limits current to nozzle while in bang-bang mode; 255=full current
-#define PID_MAX BANG_MAX // limits current to nozzle while PID is active; 255=full current
+#define PID_MAX BANG_MAX // limits current to nozzle while PID is active (see PID_FUNCTIONAL_RANGE below); 255=full current
 #if ENABLED(PIDTEMP)
   //#define PID_AUTOTUNE_MENU // Add PID Autotune to the LCD "Temperature" menu to run M303 and apply the result.
   //#define PID_DEBUG // Sends debug data to the serial port.
   //#define SLOW_PWM_HEATERS // PWM with very low frequency (roughly 0.125Hz=8s) and minimum state time of approximately 1s useful for heaters driven by a relay
   //#define PID_PARAMS_PER_HOTEND // Uses separate PID parameters for each extruder (useful for mismatched extruders)
                                   // Set/get with gcode: M301 E[extruder number, 0-2]
+  #define PID_FUNCTIONAL_RANGE 10 // If the temperature difference between the target temperature and the actual temperature
+                                  // is more than PID_FUNCTIONAL_RANGE then the PID will be shut off and the heater will be set to min/max.
   #define K1 0.95 //smoothing factor within the PID
 
   // Witbox

Marlin/example_configurations/adafruit/ST7565/Configuration.h

 // Comment the following line to disable PID and enable bang-bang.
 #define PIDTEMP
 #define BANG_MAX 255 // limits current to nozzle while in bang-bang mode; 255=full current
-#define PID_MAX BANG_MAX // limits current to nozzle while PID is active; 255=full current
+#define PID_MAX BANG_MAX // limits current to nozzle while PID is active (see PID_FUNCTIONAL_RANGE below); 255=full current
 #if ENABLED(PIDTEMP)
   //#define PID_AUTOTUNE_MENU // Add PID Autotune to the LCD "Temperature" menu to run M303 and apply the result.
   //#define PID_DEBUG // Sends debug data to the serial port.
   //#define SLOW_PWM_HEATERS // PWM with very low frequency (roughly 0.125Hz=8s) and minimum state time of approximately 1s useful for heaters driven by a relay
   //#define PID_PARAMS_PER_HOTEND // Uses separate PID parameters for each extruder (useful for mismatched extruders)
                                   // Set/get with gcode: M301 E[extruder number, 0-2]
+  #define PID_FUNCTIONAL_RANGE 10 // If the temperature difference between the target temperature and the actual temperature
+                                  // is more than PID_FUNCTIONAL_RANGE then the PID will be shut off and the heater will be set to min/max.
   #define K1 0.95 //smoothing factor within the PID
 
   // If you are using a pre-configured hotend then you can use one of the value sets by uncommenting it

Marlin/example_configurations/delta/biv2.5/Configuration.h

 // Comment the following line to disable PID and enable bang-bang.
 #define PIDTEMP
 #define BANG_MAX 255 // limits current to nozzle while in bang-bang mode; 255=full current
-#define PID_MAX BANG_MAX // limits current to nozzle while PID is active; 255=full current
+#define PID_MAX BANG_MAX // limits current to nozzle while PID is active (see PID_FUNCTIONAL_RANGE below); 255=full current
 #if ENABLED(PIDTEMP)
   //#define PID_AUTOTUNE_MENU // Add PID Autotune to the LCD "Temperature" menu to run M303 and apply the result.
   //#define PID_DEBUG // Sends debug data to the serial port.
   //#define SLOW_PWM_HEATERS // PWM with very low frequency (roughly 0.125Hz=8s) and minimum state time of approximately 1s useful for heaters driven by a relay
   //#define PID_PARAMS_PER_HOTEND // Uses separate PID parameters for each extruder (useful for mismatched extruders)
                                   // Set/get with gcode: M301 E[extruder number, 0-2]
+  #define PID_FUNCTIONAL_RANGE 10 // If the temperature difference between the target temperature and the actual temperature
+                                  // is more than PID_FUNCTIONAL_RANGE then the PID will be shut off and the heater will be set to min/max.
   #define K1 0.95 //smoothing factor within the PID
 
   // If you are using a pre-configured hotend then you can use one of the value sets by uncommenting it

Marlin/example_configurations/delta/generic/Configuration.h

 // Comment the following line to disable PID and enable bang-bang.
 #define PIDTEMP
 #define BANG_MAX 255 // limits current to nozzle while in bang-bang mode; 255=full current
-#define PID_MAX BANG_MAX // limits current to nozzle while PID is active; 255=full current
+#define PID_MAX BANG_MAX // limits current to nozzle while PID is active (see PID_FUNCTIONAL_RANGE below); 255=full current
 #if ENABLED(PIDTEMP)
   //#define PID_AUTOTUNE_MENU // Add PID Autotune to the LCD "Temperature" menu to run M303 and apply the result.
   //#define PID_DEBUG // Sends debug data to the serial port.
   //#define SLOW_PWM_HEATERS // PWM with very low frequency (roughly 0.125Hz=8s) and minimum state time of approximately 1s useful for heaters driven by a relay
   //#define PID_PARAMS_PER_HOTEND // Uses separate PID parameters for each extruder (useful for mismatched extruders)
                                   // Set/get with gcode: M301 E[extruder number, 0-2]
+  #define PID_FUNCTIONAL_RANGE 10 // If the temperature difference between the target temperature and the actual temperature
+                                  // is more than PID_FUNCTIONAL_RANGE then the PID will be shut off and the heater will be set to min/max.
   #define K1 0.95 //smoothing factor within the PID
 
   // If you are using a pre-configured hotend then you can use one of the value sets by uncommenting it

Marlin/example_configurations/delta/kossel_mini/Configuration.h

 // Comment the following line to disable PID and enable bang-bang.
 #define PIDTEMP
 #define BANG_MAX 255 // limits current to nozzle while in bang-bang mode; 255=full current
-#define PID_MAX BANG_MAX // limits current to nozzle while PID is active; 255=full current
+#define PID_MAX BANG_MAX // limits current to nozzle while PID is active (see PID_FUNCTIONAL_RANGE below); 255=full current
 #if ENABLED(PIDTEMP)
   //#define PID_AUTOTUNE_MENU // Add PID Autotune to the LCD "Temperature" menu to run M303 and apply the result.
   //#define PID_DEBUG // Sends debug data to the serial port.
   //#define SLOW_PWM_HEATERS // PWM with very low frequency (roughly 0.125Hz=8s) and minimum state time of approximately 1s useful for heaters driven by a relay
   //#define PID_PARAMS_PER_HOTEND // Uses separate PID parameters for each extruder (useful for mismatched extruders)
                                   // Set/get with gcode: M301 E[extruder number, 0-2]
+  #define PID_FUNCTIONAL_RANGE 10 // If the temperature difference between the target temperature and the actual temperature
+                                  // is more than PID_FUNCTIONAL_RANGE then the PID will be shut off and the heater will be set to min/max.
   #define K1 0.95 //smoothing factor within the PID
 
   // If you are using a pre-configured hotend then you can use one of the value sets by uncommenting it

Marlin/example_configurations/delta/kossel_pro/Configuration.h

 // Comment the following line to disable PID and enable bang-bang.
 #define PIDTEMP
 #define BANG_MAX 255 // limits current to nozzle while in bang-bang mode; 255=full current
-#define PID_MAX  125 // limits current to nozzle while PID is active; 255=full current
+#define PID_MAX  125 // limits current to nozzle while PID is active (see PID_FUNCTIONAL_RANGE below); 255=full current
 #if ENABLED(PIDTEMP)
   //#define PID_AUTOTUNE_MENU // Add PID Autotune to the LCD "Temperature" menu to run M303 and apply the result.
   //#define PID_DEBUG // Sends debug data to the serial port.
   //#define SLOW_PWM_HEATERS // PWM with very low frequency (roughly 0.125Hz=8s) and minimum state time of approximately 1s useful for heaters driven by a relay
   //#define PID_PARAMS_PER_HOTEND // Uses separate PID parameters for each extruder (useful for mismatched extruders)
                                   // Set/get with gcode: M301 E[extruder number, 0-2]
+  #define PID_FUNCTIONAL_RANGE 50 // If the temperature difference between the target temperature and the actual temperature
+                                  // is more than PID_FUNCTIONAL_RANGE then the PID will be shut off and the heater will be set to min/max.
   #define K1 0.95 //smoothing factor within the PID
 
   // Kossel Pro

Marlin/example_configurations/delta/kossel_xl/Configuration.h

 // Comment the following line to disable PID and enable bang-bang.
 #define PIDTEMP
 #define BANG_MAX 255 // limits current to nozzle while in bang-bang mode; 255=full current
-#define PID_MAX BANG_MAX // limits current to nozzle while PID is active; 255=full current
+#define PID_MAX BANG_MAX // limits current to nozzle while PID is active (see PID_FUNCTIONAL_RANGE below); 255=full current
 #if ENABLED(PIDTEMP)
   //#define PID_AUTOTUNE_MENU // Add PID Autotune to the LCD "Temperature" menu to run M303 and apply the result.
   //#define PID_DEBUG // Sends debug data to the serial port.
   //#define SLOW_PWM_HEATERS // PWM with very low frequency (roughly 0.125Hz=8s) and minimum state time of approximately 1s useful for heaters driven by a relay
   //#define PID_PARAMS_PER_HOTEND // Uses separate PID parameters for each extruder (useful for mismatched extruders)
                                   // Set/get with gcode: M301 E[extruder number, 0-2]
+  #define PID_FUNCTIONAL_RANGE 10 // If the temperature difference between the target temperature and the actual temperature
+                                  // is more than PID_FUNCTIONAL_RANGE then the PID will be shut off and the heater will be set to min/max.
   #define K1 0.95 //smoothing factor within the PID
 
   // If you are using a pre-configured hotend then you can use one of the value sets by uncommenting it

Marlin/example_configurations/makibox/Configuration.h

 // Comment the following line to disable PID and enable bang-bang.
 #define PIDTEMP
 #define BANG_MAX 255 // limits current to nozzle while in bang-bang mode; 255=full current
-#define PID_MAX BANG_MAX // limits current to nozzle while PID is active; 255=full current
+#define PID_MAX BANG_MAX // limits current to nozzle while PID is active (see PID_FUNCTIONAL_RANGE below); 255=full current
 #if ENABLED(PIDTEMP)
   //#define PID_AUTOTUNE_MENU // Add PID Autotune to the LCD "Temperature" menu to run M303 and apply the result.
   //#define PID_DEBUG // Sends debug data to the serial port.
   //#define SLOW_PWM_HEATERS // PWM with very low frequency (roughly 0.125Hz=8s) and minimum state time of approximately 1s useful for heaters driven by a relay
   //#define PID_PARAMS_PER_HOTEND // Uses separate PID parameters for each extruder (useful for mismatched extruders)
                                   // Set/get with gcode: M301 E[extruder number, 0-2]
+  #define PID_FUNCTIONAL_RANGE 10 // If the temperature difference between the target temperature and the actual temperature
+                                  // is more than PID_FUNCTIONAL_RANGE then the PID will be shut off and the heater will be set to min/max.
   #define K1 0.95 //smoothing factor within the PID
 
   // If you are using a pre-configured hotend then you can use one of the value sets by uncommenting it

Marlin/example_configurations/tvrrug/Round2/Configuration.h

 // Comment the following line to disable PID and enable bang-bang.
 #define PIDTEMP
 #define BANG_MAX 255 // limits current to nozzle while in bang-bang mode; 255=full current
-#define PID_MAX BANG_MAX // limits current to nozzle while PID is active; 255=full current
+#define PID_MAX BANG_MAX // limits current to nozzle while PID is active (see PID_FUNCTIONAL_RANGE below); 255=full current
 #if ENABLED(PIDTEMP)
   //#define PID_AUTOTUNE_MENU // Add PID Autotune to the LCD "Temperature" menu to run M303 and apply the result.
   //#define PID_DEBUG // Sends debug data to the serial port.
   //#define SLOW_PWM_HEATERS // PWM with very low frequency (roughly 0.125Hz=8s) and minimum state time of approximately 1s useful for heaters driven by a relay
   //#define PID_PARAMS_PER_HOTEND // Uses separate PID parameters for each extruder (useful for mismatched extruders)
                                   // Set/get with gcode: M301 E[extruder number, 0-2]
+  #define PID_FUNCTIONAL_RANGE 10 // If the temperature difference between the target temperature and the actual temperature
+                                  // is more than PID_FUNCTIONAL_RANGE then the PID will be shut off and the heater will be set to min/max.
   #define K1 0.95 //smoothing factor within the PID
 
   // If you are using a pre-configured hotend then you can use one of the value sets by uncommenting it

Marlin/temperature.cpp

   #endif
 
   float Temperature::pid_error[HOTENDS];
+  bool Temperature::pid_reset[HOTENDS];
 #endif
 
 #if ENABLED(PIDTEMPBED)
 #endif
 
 #if HAS_PID_HEATING
+
   void Temperature::PID_autotune(float temp, int hotend, int ncycles, bool set_result/*=false*/) {
     float input = 0.0;
     int cycles = 0;
 }
 
 #if HAS_AUTO_FAN
+
   void Temperature::checkExtruderAutoFans() {
     const int8_t fanPin[] = { EXTRUDER_0_AUTO_FAN_PIN, EXTRUDER_1_AUTO_FAN_PIN, EXTRUDER_2_AUTO_FAN_PIN, EXTRUDER_3_AUTO_FAN_PIN };
     const int fanBit[] = {
   #endif
   float pid_output;
   #if ENABLED(PIDTEMP)
-    #if ENABLED(PID_OPENLOOP)
-      pid_output = constrain(target_temperature[HOTEND_INDEX], 0, PID_MAX);
-    #else
+    #if DISABLED(PID_OPENLOOP)
       pid_error[HOTEND_INDEX] = target_temperature[HOTEND_INDEX] - current_temperature[HOTEND_INDEX];
       dTerm[HOTEND_INDEX] = K2 * PID_PARAM(Kd, HOTEND_INDEX) * (current_temperature[HOTEND_INDEX] - temp_dState[HOTEND_INDEX]) + K1 * dTerm[HOTEND_INDEX];
       temp_dState[HOTEND_INDEX] = current_temperature[HOTEND_INDEX];
-      if (target_temperature[HOTEND_INDEX] == 0) {
+      if (pid_error[HOTEND_INDEX] > PID_FUNCTIONAL_RANGE) {
+        pid_output = BANG_MAX;
+        pid_reset[HOTEND_INDEX] = true;
+      }
+      else if (pid_error[HOTEND_INDEX] < -(PID_FUNCTIONAL_RANGE) || target_temperature[HOTEND_INDEX] == 0) {
         pid_output = 0;
-        temp_iState[HOTEND_INDEX] = 0.0;
+        pid_reset[HOTEND_INDEX] = true;
       }
       else {
+        if (pid_reset[HOTEND_INDEX]) {
+          temp_iState[HOTEND_INDEX] = 0.0;
+          pid_reset[HOTEND_INDEX] = false;
+        }
         pTerm[HOTEND_INDEX] = PID_PARAM(Kp, HOTEND_INDEX) * pid_error[HOTEND_INDEX];
         temp_iState[HOTEND_INDEX] += pid_error[HOTEND_INDEX];
         iTerm[HOTEND_INDEX] = PID_PARAM(Ki, HOTEND_INDEX) * temp_iState[HOTEND_INDEX];
           pid_output = 0;
         }
       }
+    #else
+      pid_output = constrain(target_temperature[HOTEND_INDEX], 0, PID_MAX);
     #endif //PID_OPENLOOP
 
     #if ENABLED(PID_DEBUG)

Marlin/temperature.h

       #endif
 
       static float pid_error[HOTENDS];
+      static bool pid_reset[HOTENDS];
     #endif
 
     #if ENABLED(PIDTEMPBED)